Adding nacelle drag to AeroDyn

docs/source/user/aerodyn-aeroacoustics/example/AeroDyn.ipt

@@ -11,6 +11,7 @@ False TwrAero - Calculate tower aerodynamic loads? (flag)
 False FrozenWake - Assume frozen wake during linearization? (flag
 False CavitCheck - Perform cavitation check? (flag)
 False Buoyancy - Include buoyancy effects? (flag)
+False NacelleDrag - Include Nacelle Drag effects? (flag)
 True CompAA - Flag to compute AeroAcoustics calculation
 "AeroAcousticsInput.dat" AA_InputFile
 ====== Environmental Conditions ==========================================

docs/source/user/aerodyn/appendix.rst

@@ -27,7 +27,7 @@ outside of OpenFAST.
 3) AeroDyn Primary Input File 
 :download:`(primary input file example) <examples/ad_primary_example.dat>`: 
 
-The primary AeroDyn input file defines modeling options, environmental conditions (except freestream flow), airfoils, tower nodal discretization and properties, tower, hub, and nacelle buoyancy properties, as well as output file specifications.
+The primary AeroDyn input file defines modeling options, environmental conditions (except freestream flow), airfoils, tower nodal discretization and properties, tower, hub, and nacelle properties, as well as output file specifications.
 
 The file is organized into several functional sections. Each section corresponds to an aspect of the aerodynamics model. 
 

docs/source/user/aerodyn/driver.rst

@@ -375,24 +375,30 @@ An example is given below for two turbines, the first one having 3 blades, the s
 
 **Hub and nacelle inputs**
 
-The sections defining the hub and nacelle buoyancy parameters must also be reproduced for each turbine.
+The sections defining the hub and nacelle parameters must also be reproduced for each turbine.
 
 An example is given below for two turbines:
 
 .. code::
 
  ====== Hub Properties ============================================================================== [used only when Buoyancy=True]
- 7.0 VolHub - Hub volume (m^3)
- 0.0 HubCenBx - Hub center of buoyancy x direction offset (m)
+ 7.0 VolHub  - Hub volume (m^3)
+ 0.0 HubCenBx  - Hub center of buoyancy x direction offset (m)
  ====== Hub Properties ============================================================================== [used only when Buoyancy=True]
- 5.0 VolHub - Hub volume (m^3)
- 0.2 HubCenBx - Hub center of buoyancy x direction offset (m)
- ====== Nacelle Properties ========================================================================== [used only when Buoyancy=True]
- 32.0 VolNac - Nacelle volume (m^3)
- 0.3, 0.0, 0.05 NacCenB - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
- ====== Nacelle Properties ========================================================================== [used only when Buoyancy=True]
- 30.0 VolNac - Nacelle volume (m^3)
- 0.5, 0.1, 0.05 NacCenB - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
+ 5.0 VolHub - Hub volume (m^3)
+ 0.2 HubCenBx - Hub center of buoyancy x direction offset (m)
+ ====== Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
+ 32.0 VolNac - Nacelle volume (m^3)
+ 0.3, 0.0, 0.05 NacCenB - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
+ 4.67, 20.15, 20.15 NacArea - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
+ 0.5, 0.5, 0.5 NacCd - Drag coefficient for the nacelle areas defined above (-)
+ 0.43, 0, 0 NacDragAC - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)
+ ====== Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
+ 32.0 VolNac - Nacelle volume (m^3)
+ 0.3, 0.0, 0.05 NacCenB - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
+ 4.67, 20.15, 20.15 NacArea - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
+ 0.5, 0.5, 0.5 NacCd - Drag coefficient for the nacelle areas defined above (-)
+ 0.43, 0, 0 NacDragAC - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)
 
 
 **Aerodynamic tower inputs**

docs/source/user/aerodyn/examples/ad_primary_example.dat

@@ -9,6 +9,7 @@ False Echo - Echo the input to "<rootname>.AD.ech"? (flag
 False TwrAero - Calculate tower aerodynamic loads? (flag)
 False CavitCheck - Perform cavitation check? (flag) [UA_Mod must be 0 when CavitCheck=true]
 False Buoyancy - Include buoyancy effects? (flag)
+False NacelleDrag - Include Nacelle Drag effects? (flag)
 False CompAA - Flag to compute AeroAcoustics calculation [used only when Wake_Mod = 1 or 2]
 "unused" AA_InputFile - AeroAcoustics input file [used only when CompAA=true]
 ====== Environmental Conditions ===================================================================
@@ -75,9 +76,12 @@ True UseBlCm - Include aerodynamic pitching moment in calcul
 ====== Hub Properties ============================================================================== [used only when Buoyancy=True]
  0 VolHub - Hub volume (m^3)
  0 HubCenBx - Hub center of buoyancy x direction offset (m)
-====== Nacelle Properties ========================================================================== [used only when Buoyancy=True]
+====== Nacelle Properties ========================================================================== [used only when Buoyancy=True or NacelleDrag=True]
  0 VolNac - Nacelle volume (m^3)
- 0, 0, 0 NacCenB - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
+ 0, 0, 0 NacCenB - Position of nacelle center of buoyancy from yaw bearing in nacelle coordinates (m)
+ 0, 0, 0 NacArea - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
+ 0, 0, 0 NacCd - Drag coefficient for the nacelle areas defined above (-)
+ 0, 0, 0 NacDragAC - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)
 ====== Tail Fin Aerodynamics =======================================================================
 False TFinAero - Calculate tail fin aerodynamics model (flag)
 "unused" TFinFile - Input file for tail fin aerodynamics [used only when TFinAero=True]

docs/source/user/aerodyn/input.rst

@@ -45,7 +45,7 @@ AeroDyn Primary Input File
 
 The primary AeroDyn input file defines modeling options, environmental
 conditions (except freestream flow), airfoils, tower nodal
-discretization and properties, tower, hub, and nacelle buoyancy properties,
+discretization and properties, tower, hub, and nacelle properties,
 as well as output file specifications.
 
 The file is organized into several functional sections. Each section
@@ -134,6 +134,9 @@ tower, nacelle, and hub of an MHK turbine or FALSE to disable this calculation.
 If ``Buoyancy`` is TRUE, the ``MHK`` flag in the AeroDyn or OpenFAST driver 
 input file must be set to 1 or 2 to indicate an MHK turbine is being modeled.
 
+Set the ``NacelleDrag`` flag to TRUE to calculate the drag loads on the nacelle
+or FALSE to disable this calculation. 
+
 Set the ``CompAA`` flag to TRUE to run aero-acoustic calculations. This
 option is only available for ``Wake_Mod = 1`` and is not available for
 an MHK turbine. See section :numref:`AeroAcoustics` for information on how to 
@@ -451,13 +454,18 @@ Since the hub and blades are joined elements, hub buoyancy should be turned on i
 
 Nacelle Properties
 ~~~~~~~~~~~~~~~~~~
-The input parameters in this section pertain to the calculation of buoyant loads
-on the nacelle and are only used when ``Buoyancy = TRUE``.
+The input parameters in this section pertain to the calculation of buoyant and drag loads
+on the nacelle and are only used when ``Buoyancy = TRUE`` or ``NacelleDrag = TRUE``.
 
 ``VolNac`` is the volume of the nacelle and ``NacCenB``` is the 
 position (x,y,z vector) of the nacelle center of buoyancy from
 the yaw bearing in local nacelle coordinates. To neglect buoyant 
-loads on the nacelle, set ``VolNac`` to 0.
+loads on the nacelle, set ``VolNac`` to 0. Only used when ``Buoyancy = TRUE``.
+
+``NacArea`` are the projected areas (x,y,z) of the nacelle in the nacelle coordinate system, 
+``NacCd`` is the drag coefficient for the nacelle areas defined by ``NacArea``and ``NacDragAC`` is the 
+position (x,y,z vector) of the nacelle aerodynamic center from
+the yaw bearing in local nacelle coordinates. Only used when ``NacelleDrag = TRUE``.
 
 Tail fin AeroDynamics
 ~~~~~~~~~~~~~~~~~~~~~

docs/source/user/aerodyn/introduction.rst

@@ -69,7 +69,7 @@ driver code, without aero-elastic coupling.
 
 AeroDyn consists of six submodels: (1) rotor wake/induction, (2) blade
 airfoil aerodynamics, (3) tower influence on the fluid local to the
-blade nodes, (4) tower drag, (5) aeroacoustics,
+blade nodes, (4) tower and nacelle drag, (5) aeroacoustics,
 and (6) buoyancy on the blades, hub, nacelle, and tower (for MHK turbines). 
 Nacelle, hub, and tail-vane fluid influence and loading (with the exception
 of nacelle and hub buoyant loads) and wake and array effects between 
@@ -179,9 +179,15 @@ structural motion, depending on features enabled). The tower drag load
 calculation is quasi-steady and independent from the tower influence on
 flow models.
 
+Similarly, the aerodynamics drag loads on the nacelle is calculated using the 
+nacelle geometry, drag coefficients, and the local relative fluid 
+velocity between the freestream (undisturbed) flow and nacelle. The 
+nacelle drag load calculation is quasi-steady and independent from the 
+rotors influence on flow models.
+
 The primary AeroDyn input file defines modeling options, environmental
 conditions (except freestream flow), airfoils, tower nodal
-discretization and properties, tower, hub, and nacelle buoyancy properties,
+discretization and properties, tower, hub, and nacelle properties,
 as well as output file specifications. Airfoil data properties are read from
 dedicated inputs files (one for each airfoil) and include coefficients of 
 lift force, drag force, and optional pitching moment and minimum pressure 

docs/source/user/api_change.rst

@@ -42,6 +42,9 @@ FAST.Farm 75 WAT_DxDyDz 5.0,
 FAST.Farm 76 WAT_ScaleBox default WAT_ScaleBox - Flag to scale the input turbulence box to zero mean and unit standard deviation at every node [DEFAULT=False] (flag)
 FAST.Farm 77 WAT_k_Def default WAT_k_Def - Calibrated parameters for the influence of the maximum wake deficit on wake-added turbulence (set of 5 parameters: k_Def, FMin, DMin, DMax, Exp) (-) [>=0.0, >=0.0 and <=1.0, >=0.0, >DMin, >0.0] or DEFAULT [DEFAULT=[0.6, 0.0, 0.0, 2.0, 1.0 ]]
 FAST.Farm 78 WAT_k_Grad default WAT_k_Grad - Calibrated parameters for the influence of the radial velocity gradient of the wake deficit on wake-added turbulence (set of 5 parameters: k_Grad, FMin, DMin, DMax, Exp) (-) [>=0.0, >=0.0 and <=1.0, >=0.0, >DMin, >0.0] or DEFAULT [DEFAULT=[3.0, 0.0, 0.0, 12.0, 0.65] 
+AeroDyn 80\* NacArea 0, 0, 0 NacArea - Projected area of the nacelle in X, Y, Z in the nacelle coordinate system (m^2)
+AeroDyn 81\* NacCd 0, 0, 0 NacCd - Drag coefficient for the nacelle areas defined above (-)
+AeroDyn 82\* NacDragAC 0, 0, 0 NacDragAC - Position of aerodynamic center of nacelle drag in nacelle coordinates (m)
 ============================================= ======= ==================== ========================================================================================================================================================================================================
 
 \*Exact line number depends on number of entries in various preceeding tables.